Geoscience Reference
In-Depth Information
HO
CH
3
O
HO
CH
3
H
CC
CH
C
(4)
23.6%
O
(1)
16.4%
O
H
2
C
H
2
O
H
2
CH
2
O
+ OH(g),
O
2
(g)
O
CH
3
O
H
CC
O
CH
3
OH
(5)
21.2%
CH
3
H
CC
(2)
12.3%
CH
C
HO
H
2
C
CH
2
(4.54)
H
2
C
H
2
H
2
CH
2
Isoprene
CH
3
CH
3
H
CC
(6)
14.1%
H
CC
(3)
12.3%
HO
O
O
OH
O
O
H
2
H
2
H
2
H
2
Isoprene peroxy radicals
background levels. In less vegetated areas and in areas
where anthropogenic emissions are large, such as in Los
Angeles, they account for only 3 to 8 percent of ozone
above background levels.
(Paulson and Seinfeld, 1992). The
e
-folding lifetime of
isoprene against reaction with OH(g) is about thirty
minutes when [OH]
10
6
molec cm
−
3
.All
six peroxy radicals convert NO(g) to NO
2
(g). The sec-
ond and fifth radicals also create
methacrolein
and
methylvinylketone
by
=
×
5.0
O
+ NO(g) + O
2
(g)
O
CH
3
H
CH
3
H
CC
+
(4.55)
CO
CH
C
HO
O
CH
2
H
H
2
CH
2
HO
2
(g)
NO
2
(g)
Isoprene peroxy radical
Formaldehyde
Methacrolein
O
+ NO(g) + O
2
(g)
O
CH
3
H
CH
3
OH
H
CC
H
CC
(4.56)
+
CO
H
2
C
O
H
H
2
C
H
2
HO
2
(g)
NO
2
(g)
Isoprene peroxy radical
Methylvinylketone
Formaldehyde
respectively. The NO
2
(g) from these reactions produces
ozone. Methacrolein and methylvinylketone react fur-
ther with OH(g) and O
3
(g) to form products that convert
NO(g) to NO
2
(g), resulting in additional ozone.
The isoprene ozone reaction, not shown, is slower
than is the isoprene hydroxyl-radical reaction. Products
of the isoprene ozone reaction include methacrolein,
methylvinylketone, the criegee biradical, and formalde-
hyde, all of which reproduce ozone lost in the reaction
and create additional ozone.
In cities near forests, such as Atlanta, Georgia, ter-
penes can account for up to 40 percent of ozone above
4.3.7. Ozone Production from Alcohols
Alcohols, which can be distilled from corn, grapes,
potatoes, sugarcane, molasses, and artichokes, among
other farm products, have been used as an engine fuel
since April 1, 1826, when Orford, New Hampshire
native
Samuel Morey
(1762-1843) patented the first
internal combustion engine. His engine ran on
ethanol
[C
2
H
5
OH(g)] and turpentine. In September 1829, his
engine was used to power a 5.8-m-long boat up the
Connecticut River at seven to eight miles per hour.
Search WWH ::
Custom Search